Field of the Invention
The invention relates to a generator switch including phase conductors each having one disconnector, one vacuum switch with horizontally disposed pole gaps and one drive device driving switching chambers.
A known generator switch is constructed in such a way that it has one inner conductor and outer encapsulation per phase. The outer encapsulation provides external screening for magnetic fields of the inner conductors. Due to that encapsulation, even relatively high currents are possible, so that generator switches can nowadays be used for rated currents up to about 50 kiloamperes. The inner conductors are tubular and may be rolled if their diameters are large. The outer encapsulation is likewise rolled, and both the inner conductor and the outer conductor are made of aluminum.
Compressed-air switches or SF.sub.6 switches have been used as switching devices. A generator switch in which vacuum switching chambers are used has been disclosed in the Siemens Prospectus entitled "Vakuum-Generatorschalter Modul FG 10" [Vacuum generator switch module FG 10], Order No. E 50001U229-A19, 2.93 Standard. In that case, the vacuum chambers are located outside a central cable run, with only one vacuum switch (having three chambers) being accommodated in each phase line. A rotary disconnector is provided downstream of the vacuum switch, in the transformer direction.
The advantages of such vacuum chambers are a low maintenance requirement. However, because of DC/AC components close to the generator, vacuum chambers cause problems since there are no zero crossings, for which reason the Siemens Company has installed a time delay for the generator switch, in order to obtain a zero crossing.